The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of

Options

A. Insertional inactivation of alphagalactosidase in recombinant bacteria
B. Inactivation of glycosidase enzyme in recombinant bacteria
C. Non-recombinant bacteria containing beta - galactosidase
D. Insertional inactivation of alphagalac- tosidase in non-recombinant bacteria

Answer

C

Explanation

In insertional inantivation a recombinant DNA is inserted within the coding sequence of enzyme `beta`- galactosidase. If the plasmid in the bacteriadoes not have the insert (i.e., non- recombinants) then the chromogenic substrate gives blue coloured colonies. Presence of the insert (i.e., recombinants) leads to inactivation of the `beta`- galactosidase enzyme thus the colonies do not produce any colour.
Option (a) is wrong, it should be `beta` galactosidase
Option (b) is wrong, it should be galactosidase instead of glycosidase
Option (c) is correct, as the non- recombinants have the `beta` galactosidase enzymes intact.
Option (d) is wrong it should be ''Insertional inactivation of `beta" "ul("galactosidase")" of "ul("recombinant bacteria''").`